文献类型：期刊文献

英文题名：Highly stereoselective Pictet-Spengler reaction of D-tryptophan methyl ester with piperonal:: convenient syntheses of Cialis (Tadalafil), 12a-epi-Cialis, and their deuterated analogues

作者：Shi, Xiao-Xin[1];Liu, Shi-Ling[1];Xu, Wei[1];Xu, Yu-Lan[1]

机构：[1]E China Univ Sci & Technol, Dept Pharmaceut Engn, Sch Pharm, Shanghai 200237, Peoples R China

年份：2008

卷号：19

期号：4

起止页码：435

外文期刊名：TETRAHEDRON-ASYMMETRY

收录：;WOS:【SCI-EXPANDED(收录号:WOS:000255350500006)，CCR-EXPANDED(收录号:WOS:000255350500006)】；

语种：英文

摘要：The acid-catalyzed Pictet-Spengler reaction Of D-tryptophan methyl ester with piperonal in acetic acid has been reported, the best stereo selectivity (cis/trans = 92:8) was obtained with benzoic acid as the catalyst. The Pictet-Spengler reaction Of D-tryptophan methyl ester hydrochloride with piperonal in various solvents has been extensively studied, the solvent-dependence of stereoselectivities could be principally attributed to the solubility-difference between cis and trans products 5-HCl in the used solvent, the best stereoselectivity (cis/trans = 99: 1) was obtained using nitromethane or acetonitrile as the solvent. A base-catalyzed epimerization at 12a-position of Cialis 1 (tadalafil) in a DMSO-containing solvent was also exploited. Cialis, 12a-epi-Cialis 2, deuterium-labeled 3,3,12a-d(3)-Cialis 3, and 3,3,12a-d(3)-12a-epi-Cialis 4 were efficiently synthesized from D-tryptophan methyl ester hydrochloride. (C) 2008 Elsevier Ltd. All rights reserved.